The present inventive subject matter relates generally to the art of printable or print receptive topcoats. Particular relevance is found in connection with a printable or print receptive topcoat that is applied over polyolefin materials for UV (ultraviolet) printing applications, and accordingly the present specification makes specific reference thereto. However, it is to be appreciated that aspects of the present inventive subject matter are also equally amenable to the topcoating of other filmic or face materials and/or other like applications.
Various formulations of printable or print receptive topcoatings, e.g., for polyolefin and/or other filmic or face materials, are generally known in the art. For example, a printable or print receptive topcoat based on a combination of polyacrylates and polyurethanes is described in U.S. Patent Application Publication, Pub. No. US 2004/0197572 A1, which is incorporated by reference herein in its entirety. One drawback of these types of compositions is the moderate anchorage of the topcoat to the face material. Furthermore, these types of compositions tend to cause problems with blocking, i.e., the unwanted adhesion of the dried topcoat to the backside of the filmic face material after production of the intermediate topcoated material. Another drawback to these compositions is their tendency to bond with silicones present in the release system which can result in undesired effects on the printing performance.
Another topcoat composition is described in the Patent Cooperation Treaty Application, International Pub. No. WO 02/38382 A1, which is incorporated by reference herein in its entirety. In the foregoing, a combination of various acrylic resins is disclosed. These topcoat compositions, however, suffer from poor anchorage of the topcoat to the substrate as well as from poor chemical resistance.
Another printable or print receptive topcoating is disclosed in U.S. Patent Application Publication, Pub. No. US 2007/116905 A1, which is incorporated by reference herein in its entirety. The print receptive topcoat described therein is composed of a water dispersible polyether urethane and a water dispersible polyester urethane.
In any event, the use of different formulations of printable or print receptive topcoatings can be problematic or limited in one or more ways. Examples of some frequently encountered problems or limitations include undesirable pinholing and/or blocking and/or poor ink-anchorage characteristics. In particular, pinholing may be caused by silicone contamination (e.g., obtained from a liner applied to the backside of the underlying film or other face material on which the topcoat is being deposited), and blocking can result by adhesion of the topcoat to the backside of the underlying film or face material. Still further, it is commonly advantageous for the topcoating to exhibit other desirable characteristics such as, good print quality, significant water resistance, appropriate gloss, suitable optical properties (e.g., haze, clarity and/or total transmittance), etc.
Accordingly, a new and/or improved printable or print receptive topcoating is disclosed which addresses the above-referenced problem(s) and/or others.